Cast 64 bit off_t to 32 bit size_t
Some systems have sizeof(off_t) == 8 while sizeof(size_t) == 4.
This implies that we are able to access and work on files whose
maximum length is around 2^63-1 bytes, but we can only malloc or
mmap somewhat less than 2^32-1 bytes of memory.
On such a system an implicit conversion of off_t to size_t can cause
the size_t to wrap, resulting in unexpected and exciting behavior.
Right now we are working around all gcc warnings generated by the
-Wshorten-64-to-32 option by passing the off_t through xsize_t().
In the future we should make xsize_t on such problematic platforms
detect the wrapping and die if such a file is accessed.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/combine-diff.c b/combine-diff.c
index 6d928f2..3a9b32f 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -684,7 +684,7 @@
goto deleted_file;
if (S_ISLNK(st.st_mode)) {
- size_t len = st.st_size;
+ size_t len = xsize_t(st.st_size);
result_size = len;
result = xmalloc(len + 1);
if (result_size != readlink(elem->path, result, len)) {
@@ -697,7 +697,7 @@
}
else if (0 <= (fd = open(elem->path, O_RDONLY)) &&
!fstat(fd, &st)) {
- size_t len = st.st_size;
+ size_t len = xsize_t(st.st_size);
size_t sz = 0;
int is_file, i;
